The present invention is directed generally to a passive solar heating system for buildings and more particularly to a modular visually transmitting thermal storage device adapted to be placed interiorly of and adjacent to solar-gain fenestration.
Passive solar heating of buildings is attractive because of relatively low cost, long-term reliability and operational simplicity. A passive system absorbs and thermalizes solar energy and then transfers heat through a thermal storage medium to the building heating load without the use of active components such as mechanical pumps. Passive solar heating has commonly been accomplished by either a Trombe wall or a direct gain system. Both of these systems have problems which limit their applications, however. The Trombe walls necessarily obstruct the view and lighting from windows and also have such substantial weight and space requirements as to be impractical for retrofit construction in existing buildings. Large window direct gain systems, on the other hand, commonly have problems of glare, photodegradation and large fluctuations of air and mean radiant temperature.
Many of these problems were resolved by the new passive heating system of applicant's U.S. Pat. No. 4,286,576 which was issued on Sept. 1, 1981. That new system presents a visually transparent modular thermal storage wall that is analogous in heating function to a Trombe wall but analogous to tinted glazing in its daylighting, visual and direct gain performance. The system consists of transparent modules filled with a clear, water-based thermal storage liquid and a semi-transparent tinted solar absorber plate assembled into a wall structure of the desired dimensions for a given installation.
Whereas the new passive heating system of U.S. Pat. No. 4,286,576 is believed to have been a significant advance in the art, certain problems were encountered which are solved by the improvements of the present invention. Such problems relate to radiative summer heat gains and winter heat losses, evaporation and contamination of the transparent thermal storage liquid, construction costs and aesthetic considerations of the triple walled containment structure of the original design.
Accordingly, a primary object of the invention is to provide an improved visually transmitting passive solar energy thermalization and storage device.
Another object is to provide a visually transmitting thermal storage device having an exterior surface which is highly transmissive of radiation in the solar spectral region but highly reflective of longer wavelengths in the infrared region.
Another object is to provide a transparent solar energy thermal storage device which, although not hermetically sealed, includes means for preventing evaporation of the thermal storage liquid.
Another object is to provide a transparent solar energy thermal storage device including means for preventing contamination of the thermal storage liquid.
Another object is to provide a transparent solar energy thermal storage device which is simple and economical in construction, aesthetically attractive in appearance and flexible for interior integration in a wide range of building types.
Another object is to provide a visually transmitting solar energy thermal storage device which is practical for use in both retrofit and new construction.